Post by KevReillyUK in ROAD KILL (ZX Spectrum Next) comments

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This is a great little Frogger game. Missing a couple of features from the arcade version, but with its own gameplay quirks and level-to-level visual changes that keep it interesting. And for anyone learning NextBASIC the fully commented source and documentation are a great resource. It's a really good demonstration of what can be achieved in NextBASIC.

Tip: for anyone using an 8BitDo M30 or similar controller in Kempston mode, adding the following line to the program will let you start a joystick-controlled game by pressing the joypad's "A" button:

5101 IF %(( IN 49150)&1)=0 THEN PROC getCTRL(1): PROC tuneST(): ENDPROC

This may also work with other multi-button controllers that map a spare button to the ENTER key by default, but I can't test this.

(Thanks to the author for permitting me to modify his code, and suggesting I post it here.)

Kevman3D2 years ago

Awesome stuff! Thanks for sharing the line of code for everyone to add if they want to mod the game a little!

Being able to start the game with the 'fire' button of your controller is more efficient then pressing a key each time (and handy to start a new game if you're sitting back on the couch with the Next on the coffee table far away - lol!)

sinclairphotography2 years ago

great option to add the line of code - be aware though that if you own hardware and have previously used the config option to map the 8 bit do pads to the "sega" option (whch is the option to ensure correct mapping on the 3 buttons) it may change the button press from button A to either B or C if youre using a different config like the kempston option. I wonder if in a game theres a way to detect what the config is and alert the user they need to change their config (or have the game adjust itself accordingly).

Threetwosevensixseven2 years ago

The joystick config is available though REG 5: https://gitlab.com/SpectrumNext/ZX_Spectrum_Next_FPGA/-/blob/master/cores/zxnext/nextreg.txt#L99

the main problem with changing it is that users expect to be in control of it themselves. It’s not reset by the OS when you do a soft reset, only a hard reset.

A typical way round that is for a game to read the config, change it, read the sticks then immediately restore the config. Warhawk does that, for example.

KevReillyUK2 years ago

It's probably over(road)kill for this purpose where the game itself already works and reading the "A" button was a cheap QOL hack, but anyone looking at adding general joystick support to NextBASIC might want to look at paulossilva's GameInput driver:

https://github.com/paulossilva/gameinput

It's possible that later additions to NextZXOS might render it obsolete, but for now it's about the simplest way of adding joystick support. I used it to modify the TAP loader so I could choose the mode using UP, DOWN, LEFT, RIGHT, FIRE on the joypad in addition to 1, 0, 4, P, N on the keyboard (hacking code for a more lean-back experience is something of a pattern for me) and it worked perfectly. Of course later revisions of NextZXOS also render this particular use largely pointless with the ability to remember launch configurations, but it was a good test for the joystick driver.

Definitely worth a look if you're going to add joystick support, especially reconfigurable joystick support, to your program.

itch.io

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